Buoyancy is the upward force that a fluid exerts on an object immersed in it. It is a result of the difference in pressure exerted by the fluid on the bottom and top of the object.
Archimedes' principle states that the buoyant force on an object is equal to the weight of the fluid that the object displaces. This principle is used to calculate the buoyancy of an object.
The density of an object affects its buoyancy because the more dense an object is, the more mass it has and the more it will sink in a fluid. Objects with less density will float because their weight is less than the buoyant force acting on them.
The shape of an object affects its buoyancy because the more surface area an object has, the more water it will displace and the more buoyant force it will experience. This is why objects with large, hollow shapes tend to float more easily.
Different fluids have different densities, so they will affect the buoyancy of an object differently. For example, an object that floats in water may not float in a denser fluid like oil. Additionally, the buoyant force will be greater in denser fluids, making it easier for objects to float.